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This sort of problems can be handled with a DBMS engine.

Something like this?

#!/usr/bin/perl -w use strict; use DBI; my @data = ( ['2004-02-01 07:01', 82], ['2004-02-01 11:38', 172], ['2004-02-01 22:48', 154], ['2004-02-02 05:38', 107], ['2004-02-02 13:20', 117], ['2004-02-02 23:48', 188]); my $dbh = DBI->connect("dbi:SQLite:averages","","") or die $DBI::errstr; unless ( -s "averages") { $dbh->do(qq{ CREATE TABLE averages ( d datetime not null, val INTEGER)}) or die $DBI::errstr; for (@data) { $dbh->do( qq{INSERT INTO averages VALUES (?, ?)}, undef, @$_) or die $DBI::errstr } } my $query = qq{ SELECT substr(d,1,10) as day, CASE WHEN substr(d,12,2) BETWEEN 4 AND 12 THEN "1 morning" WHEN substr(d,12,2) BETWEEN 13 AND 18 THEN "2 afternoon" WHEN substr(d,12,2) BETWEEN 19 AND 24 THEN "3 evening" ELSE "4 night" END AS tm, AVG(val) FROM averages GROUP BY day, tm ORDER BY day, tm }; my $averages = $dbh->selectall_arrayref($query) or die $DBI::errstr; printf "%-10s %-15s %5.2f\n", @$_ for @$averages; __END__ output: 2004-02-01 1 morning 127.00 2004-02-01 3 evening 154.00 2004-02-02 1 morning 107.00 2004-02-02 2 afternoon 117.00 2004-02-02 3 evening 188.00

You can add/remove/modify the intervals by acting on the CASE statement inside the query.

If you want an average by time only, without the days, then use this query:

my $query = qq{ SELECT CASE WHEN substr(d,12,2) BETWEEN 4 AND 12 THEN "1 morning" WHEN substr(d,12,2) BETWEEN 13 AND 18 THEN "2 afternoon" WHEN substr(d,12,2) BETWEEN 19 AND 24 THEN "3 evening" ELSE "4 night" END AS tm, AVG(val) FROM averages GROUP BY tm ORDER BY tm }; my $averages = $dbh->selectall_arrayref($query) or die $DBI::errstr; printf "%-15s %5.2f\n", @$_ for @$averages; __END__ output: 1 morning 120.33 2 afternoon 117.00 3 evening 171.00
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In reply to Re: Data averages by time of day by gmax
in thread Data averages by time of day by blue_cowdawg

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